A reversed-flow gas-chromatography (RF-GC) apparatus for the measurement of binary diffusion coefficients is described and utilized to measure the binary diffusion coefficients for several systems at temperatures from (300 to 723)K. Hydrocarbons are detected using flame ionization detection, and inert species can be detected by thermal conductivity. The present apparatus has been utilized to me...

2014 It is shown that the cross-over concentration between dilute and semi-dilute solutions is the same for dynamical properties as for static properties of flexible polymers in a good solvent. For semi-dilute solutions, the exponent 03B2 in the concentration dependence of the diffusion coefficient of a blob Dc ~ C03B2 is expected to depend on both temperature and concentration. The variation o...

Trapping of interstitial atoms by foreign substitutional atoms is a phenomenon that significantly influences the chemistry of the system as well as the diffusivity of the interstitial components. In their previous paper (Svoboda et al 2013 Modelling Simul. Mater. Sci. Eng. 21 065012), the present authors determined the trapping energy and the chemical diffusion coefficient of an interstitial co...

We present a finite temperature calculation of the transverse spin-diffusion coefficient, D⊥, in a dilute degenerate Fermi gas in the presence of a small external magnetic field, H. While the longitudinal diffusion coefficient displays the conventional low-temperature Fermi-liquid behavior, D‖ ∝ T−2, the corresponding results for D⊥ show three separate regimes: (a) D⊥ ∼ H−2 for T ≪ H; (b) D⊥ ∼ ...

In this work, the Z-average, effective, apparent diffusion coefficients and their poly-dispersity indexes were investigated for dilute poly-disperse homogeneous spherical particles in dispersion where the Rayleigh-Gans-Debye approximation is valid. The results reveal that the values of the apparent and effective diffusion coefficients at a scattering angle investigated are consistent and the di...

This paper concerns the Taylor-Aris dispersion of a dilute solute concentration immersed in a highly heterogeneous fluid flow having possibly sharp interfaces (discontinuities) in the diffusion coefficient and flow velocity. The focus is two-fold: (i) Calculation of the longitudinal effective dispersion coefficient, and (ii) sample path analysis of the underlying stochastic process governing th...

Reversible diffusion limited cluster aggregation of hard spheres with rigid bonds was simulated and the self-diffusion coefficient was determined for equilibrated systems. The effect of increasing attraction strength was determined for systems at different volume fractions and different interaction ranges. It was found that the slowing down of the diffusion coefficient due to crowding is decoup...

Flexible stationary diffusion-type models are developed that can fit both the marginal distribution and the correlation structure found in many time series from e.g. finance and turbulence. Diffusion models with linear drift and a known and prespecified marginal distribution are studied, and the diffusion coefficients corresponding a large number of common probability distributions are found ex...

We study a shadow limit (the infinite diffusion coefficient-limit) of a system of ODEs coupled with a semilinear heat equation in a bounded domain with Neumann boundary conditions. In the literature, it was established formally that in the limit, the original semilinear heat equation reduces to an ODE involving the space averages of the solution to the semilinear heat equation and of the nonlin...